The invention relates to a high-pressure gas discharge lamp comprising a translucent lamp vessel, which is sealed in a vacuumtight manner, which is filled with an ionizable gas and which has electrodes which project into the lamp vessel and are connected to current supply conductors, which extend to the exterior through the wall of the lamp vessel, the electrodes each comprising a rod of mainly tungsten, which has near its tip projecting inside the lamp vessel a helical winding of wire of mainly tungsten, a first layer of turns being present around the rod and a second layer of turns being arranged to surround the first layer, this winding being fixed on the rod and the wire of this winding having ends with end faces.
Such a lamp is known from U.S. Pat. No. 3,170,081.
The winding around the rod of an electrode solely has for its object to obtain a satisfactory temperature variation over the electrode, or additionally to hold electron-emitting material.
It is mostly necessary for the winding to be fixed on the rod, for example, by deforming a turn in the hot state or by ensuring that the latter is clamped around the rod, or by welding the winding to the rod.
In the lamp according to the said U.S. Pat. No. 3,170,081, the first layer of turns is a body which is slipped with clearance around the rod and is fixed on it, while the other layer of turns is a separate body which is slipped around the first layer. In order to fix the second layer of turns, the first layer of turns has a projecting wire portion at its end remote from the tip of the rod of the electrode and the other layer of turns has at the corresponding end a wire portion bent towards the rod. This electrode construction renders the manufacture of the electrodes and hence of the lamp difficult. The invention has for its object to provide a high-pressure gas discharge lamp of the kind mentioned, whose electrodes have simple construction that can be readily manufactured, while nevertheless the winding is firmly fixed on the rod.